Is There Light at the Ends of the Tunnel? Wireless Sensor Networks for Adaptive Lighting in Road Tunnels

Existing deployments of wireless sensor networks (WSNs) are often conceived as stand-alone monitoring tools. In this paper, we report instead on a deployment where the WSN is a key component of a closed-loop control system for adaptive lighting in operational road tunnels. WSN nodes along the tunnel walls report light readings to a control station, which closes the loop by setting the intensity of lamps to match a legislated curve. The ability to match dynamically the lighting levels to the actual environmental conditions improves the tunnel safety and reduces its power consumption. The use of WSNs in a closed-loop system, combined with the real-world, harsh setting of operational road tunnels, induces tighter requirements on the quality and timeliness of sensed data, as well as on the reliability and lifetime of the network. In this work, we test to what extent mainstream WSN technology meets these challenges, using a dedicated design that however relies on wellestablished techniques. The paper describes the hw/sw architecture we devised by focusing on the WSN component, and analyzes its performance through experiments in a real, operational tunnel

A nearly zero-energy microgrid testbed laboratory: Centralized control strategy based on SCADA system

Currently, despite the use of renewable energy sources (RESs), distribution networks are facing problems, such as complexity and low productivity. Emerging microgrids (MGs) with RESs based on supervisory control and data acquisition (SCADA) are an effective solution to control, manage, and finally deal with these challenges. The development and success of MGs is highly dependent on the use of power electronic interfaces. The use of these interfaces is directly related to the progress of SCADA systems and communication infrastructures. The use of SCADA systems for the control and operation of MGs and active distribution networks promotes productivity and efficiency. This paper presents a real MG case study called the LAMBDA MG testbed laboratory, which has been implemented in the electrical department of the Sapienza University of Rome with a centralized energy management system (CEMS). The real-time results of the SCADA system show that a CEMS can create proper energy balance in a LAMBDA MG testbed and, consequently, minimize the exchange power of the LAMBDA MG and main grid

Getting expert systems off the ground: Lessons learned from integrating model-based diagnostics with prototype flight hardware

As an initial attempt to introduce expert system technology into an onboard environment, a model based diagnostic system using the TRW MARPLE software tool was integrated with prototype flight hardware and its corresponding control software. Because this experiment was designed primarily to test the effectiveness of the model based reasoning technique used, the expert system ran on a separate hardware platform, and interactions between the control software and the model based diagnostics were limited. While this project met its objective of showing that model based reasoning can effectively isolate failures in flight hardware, it also identified the need for an integrated development path for expert system and control software for onboard applications. In developing expert systems that are ready for flight, artificial intelligence techniques must be evaluated to determine whether they offer a real advantage onboard, identify which diagnostic functions should be performed by the expert systems and which are better left to the procedural software, and work closely with both the hardware and the software developers from the beginning of a project to produce a well designed and thoroughly integrated application

Autonomous Multi-Chemistry Secondary-Use Battery Energy Storage

Battery energy storage is poised to play an increasingly important role in the modern electric grid. Not only does it provide the ability to change the time-of-day and magnitude of energy produced by renewable resources like wind and solar, it can also provide a host of other 3ancillary grid-stabilizing services. Cost remains a limiting factor in deploying energy storage systems large enough to provide these services on the scale required by an electric utility provider. Secondary-use electric vehicle batteries are a source of inexpensive energy storage materials that are not yet ready for the landfill but cannot operate in vehicles any longer. However, the wide range of manufacturers using different battery chemistries and configurations mean that integrating these batteries into a large-format system can be difficult. This work demonstrates methods for the autonomous integration and operation of a wide range of stationary energy storage battery chemistries. A fully autonomous battery characterization is paired with a novel system architecture and transactive optimization to create a system which can provide utility-scale energy services using a multitude of battery chemistries in the same system. These claims are verified using a combination of in-situ testing and a computer modelling testbed. Results are presented which demonstrate the ability of the system to combine a wide range of batteries into an effective single system

Implementation of Solar Irradiance Forecasting Using Markov Switching Model and Energy Management System

Photovoltaic (PV) systems integration is increasingly being used to reduce fuel consumption in diesel-based remote microgrids. However, uncertainty and low correlation of PV power availability with load reduce the benefits of PV integration. These challenges can be handled by introducing reserve, which however leads to increased operational cost. Solar irradiance forecasting helps to reduce reserve requirement, thereby improving the utilization of PV energy. In this thesis, a new solar irradiance forecasting method for remote microgrids based on the Markov Switching Model (MSM) is presented. This method uses locally available data to predict one-day-ahead solar irradiance for scheduling energy resources in remote microgrids. The model considers the past solar irradiance data, the Clear Sky Irradiance (CSI), and the Fourier basis functions to create linear models for three regimes or states: high, medium, and low energy regimes for a day corresponding to sunny, mildly cloudy, and extremely cloudy days, respectively. The case study for Brookings, SD, discussed in this thesis, resulted in an average Mean Absolute Percentage Error (MAPE) of 31.8% for five years, 2001 to 2005, with higher errors during summer months than during winter months. The solar irradiance forecasting method was implemented in OPAL-RT real-time digital simulator using PV panels as sensors. For forecasting irradiance, the first four hours of irradiance data in the morning are required. These data were measured using the solar panels rather than pyranometers as the sensors . A case study for real-time irradiance forecasting in Brookings on June 9, 2015 showed RMSE and MAPE of 131.08W=m2 and 45.45%, respectively. The improvement of renewable integration is the future and present prospects for power utilization. Microgrids experience several constraints such as integration of intermittent renewable sources, costlier reliability improvements, restricted expansion of the microgrid system, growth in load, etc. Hence, more research in this field of study is required and a complete laboratory scale microgrid testbed is needed for experimenting different types of microgrid topologies and for studying the coordination of individual components with a well-defined energy management scheme. In this thesis, the development of a laboratory scale single-phase microgrid testbed along with the implementation of microgrid’s Energy Management System (EMS) are discussed. The testbed was developed using central controller and Commercial Off-The-Shelf (COTS) equipment. The EMS comprised of double layers: schedule layer and real-time dispatch layer. A case study conducted for the implementation of the EMS showed that the difference in the scheduled and the dispatched powers were handled by the generator and the energy storage system themselves

Model for Predicting Bluetooth Low Energy Micro-Location Beacon Coin Cell Battery Lifetime

Bluetooth Low Energy beacon devices, typically operating on coin cell batteries, have emerged as key components of micro-location wireless sensor networks. To design efficient and reliable networks, designers require tools for predicting battery and beacon lifetime, based on design parameters that are specific to micro-location applications. This design science research contributes to the implementation of an artifact functioning as a predictive tool for coin cell battery lifetime when powering Bluetooth Low Energy beacon devices. Building upon effective and corroborated components from other researchers, the Beacon Lifetime Model 1.0 was developed as a spreadsheet workbook, providing a user interface for designers to specify parameters, and providing a predictive engine to predict coin cell battery lifetime. Results showed that the measured and calculated predictions were consistent with those derived through other methodologies, while providing a uniquely extensible user interface which may accommodate future work on emerging components. Future work may include research on real world scenarios, as beacon devices are deployed for robust micro-location applications. Future work may also include improved battery models that capture increasingly accurate performance under micro-location workloads. Beacon Lifetime Model 1.x is designed to incorporate those emerging components, with Beacon Lifetime Model1.0 serving as the initial instantiation of this design science artifact

Modeling the Temperature Bias of Power Consumption for Nanometer-Scale CPUs in Application Processors

We introduce and experimentally validate a new macro-level model of the CPU temperature/power relationship within nanometer-scale application processors or system-on-chips. By adopting a holistic view, this model is able to take into account many of the physical effects that occur within such systems. Together with two algorithms described in the paper, our results can be used, for instance by engineers designing power or thermal management units, to cancel the temperature-induced bias on power measurements. This will help them gather temperature-neutral power data while running multiple instance of their benchmarks. Also power requirements and system failure rates can be decreased by controlling the CPU's thermal behavior. Even though it is usually assumed that the temperature/power relationship is exponentially related, there is however a lack of publicly available physical temperature/power measurements to back up this assumption, something our paper corrects. Via measurements on two pertinent platforms sporting nanometer-scale application processors, we show that the power/temperature relationship is indeed very likely exponential over a 20{\deg}C to 85{\deg}C temperature range. Our data suggest that, for application processors operating between 20{\deg}C and 50{\deg}C, a quadratic model is still accurate and a linear approximation is acceptable.Comment: Submitted to SAMOS 2014; International Conference on Embedded Computer Systems: Architectures, Modeling, and Simulation (SAMOS XIV

STUDY OF CONTROL SCHEMES FOR SERIES HYBRID-ELECTRIC POWERTRAIN FOR UNMANNED AERIAL SYSTEMS

Hybrid-Electric aircraft powertrain modeling for Unmanned Aerial Systems (UAS) is a useful tool for predicting powertrain performance of the UAS aircraft. However, for small UAS, potential gains in range and endurance can depend significantly on the aircraft flight profile and powertrain control logic in addition to the subsequent impact on the performance of powertrain components. Small UAS aircraft utilize small-displacement engines with poor thermal efficiency and, therefore, could benefit from a hybridized powertrain by reducing fuel consumption. This study uses a dynamic simulation of a UAS, representative flight profiles, and powertrain control logic approaches to evaluate the performance of a series hybrid-electric powertrain. Hybrid powertrain component models were developed using lookup tables of test data and model parameterization approaches to generate a UAS dynamic system model. These models were then used to test three different hybrid powertrain control strategies for their ability to provide efficient IC engine operation during the charging process. The baseline controller analyzed in this work does not focus on optimizing fuel efficiency. In contrast, the other two controllers utilize engine fuel consumption data to develop a scheme to reduce fuel consumption during the battery charging operation. The performance of the powertrain controllers is evaluated for a UAS operating on three different representative mission profiles relevant to cruising, maneuvering, and surveillance missions. Fuel consumption and battery state of charge form two metrics that are used to evaluate the performance of each controller. The first fuel efficiency-focused controller is the ideal operating line (IOL) strategy. The IOL strategy uses performance maps obtained by engine characterization on a specialized dynamometer. The simulations showed the IOL strategy produced average fuel economy improvements ranging from 12%-15% for a 30-minute mission profile compared to the baseline controller. The last controller utilizes fuzzy logic to manage the charging operations while maintaining efficient fuel operation where it produced similar fuel saving to the IOL method but were generally higher by 2-3%. The importance of developing detailed dynamic system models to capture the power variations during flight with fuel-efficient powertrain controllers is key to maximizing small UAS hybrid powertrain performance in varying operating conditions

Mesh networks for handheld mobile devices

Mesh communications emerge today as a very popular networking solution. Mesh networks have a decentralized and multihop design. These characteristics arouse interest in research for relevant novel features, such as cooperation among nodes, distribution of tasks, scalability, communication with limited infrastructure support, and the support of mobile devices as mesh nodes. In addition to the inexistence of a solution that implements mesh networks with mobile devices at the data link layer (Layer 2), there is also a need to reconsider existing metrics with new information to tackle the intrinsic characteristics of mobile devices, e.g., the limited energy resources of their battery. To tackle this problem, this thesis presents a detailed study about projects, routing protocols and metrics developed in the area of mesh networks. In addition, two data link layer solutions, Open802.11s and B.A.T.M.A.N-advanced, have been adapted and deployed in a real mesh network testbed with off the shelf routers devices installed with a customized operating system. From this testbed, Open802.11s has proved to offer better performance than B.A.T.M.A.N-advanced. Following this, a breakthrough in this work has been the integration of the 802.11s on an Android mobile device and its subsequent incorporation in the mesh network. This allowed the study of eventual limitations imposed by the mobile device on the operation of the mesh network, namely performance and energy scarcity. With this, another major novelty has followed, by designing, implementing and evaluating several energy related metrics regarding the battery status of mobile devices. This has enabled the participation of mobile devices in mesh routing paths in an efficient way. Our main objective was to implement a mesh network with mobile devices. This has been achieved and validated through the evaluation of diverse testing scenarios performed in a real mesh testbed. The obtained results also show that the operation of a mesh with mobile devices can be enhanced, including the lifetime of mobile devices, when an energy-aware metric is used.As redes mesh surgem hoje em dia como uma solução de rede em crescimento e expansão. Neste tipo de redes o comportamento entre os nós é descentralizado e numa topologia de multihop. Estas características despertam interesse na pesquisa e desenvolvimento de novas funcionalidades tais como: cooperação entre nós, distribuição de tarefas, escalabilidade da rede e comunicações mesmo em casos de uma infraestrutura limitada e o suporte de dispositivos móveis como nós de uma rede mesh. Associado à inexistência de um projecto que implemente redes mesh em dispositivos móveis na camada de ligação de dados (Layer 2), surge a necessidade de repensar as métricas já existentes com novas informações que façam face às novas características dos dispositivos móveis, neste caso, os recursos limitados de bateria. Por forma a resolver este problema, este trabalho apresenta um estudo detalhado sobre os projetos, protocolos de routing e métricas desenvolvidas na área das redes mesh. Além disso, duas soluções que utilizam a camada de ligação de dados, Open802.11s e BATMAN-advanced, estes foram adaptadao e implementados num testbed real utilizando routers com um sistema operacional costumizado instalado. Deste testbed, concluiu-se que o Open802.11s obtem um melhor desempenho que o BATMAN-advanced. Assim, um dos avanços deste trabalho foi a integração do Open802.11s num dispositivo móvel Android e sua posterior incorporação na rede mesh. Isto permitiu o estudo de eventuais limitações impostas pelo dispositivo móvel ao funcionar numa rede mesh, ou seja, desempenho e a escassez de energia. Com isso, foi concebida outra novidade, através da concepção, avaliação e implementação de várias métricas relacionadas com a energia e que têm por base o estado da bateria do dispositivo. Isto permitiu que os dispositivos móveis participem na rede mesh e a sua gestão de bateria seja feita de forma eficiente. O principal objectivo era a implementação de uma rede mesh com dispositivos móveis. Este foi alcançado e validado através de diversos cenários de teste reais. Os resultados obtidos demonstram também que o funcionamento de uma rede mesh com dispositivos móveis pode ser melhorada, incluindo o tempo de vida dos dispositivos móveis, quando uma métrica que considera a energia é utilizada

Testialustan suunnittelu hybridiajoneuvojen hardware-in-the-loop simulaatioihin

Recent changes to vehicle type-approval regulations have increased demand for testing methods, which better represent real-world driving conditions. Hardware-in-the-Loop (HIL) simulation is seen as an attractive alternative for pure simulations and real-world operation measurements. The goal of this work was to provide a functional testbed for engine testing, as well as for HIL simulations of Hybrid Electric Vehicles (HEVs). In addition, a state-of-the-art review of HIL was considered an important goal of the work. The theory behind HIL, and real-time systems in general, is depicted using a wide variety of examples from automotive applications relating to hybrid power sources. The knowledge gained from the literature was used to design and build a testbed in a form of an engine dynamometer. The testbed can be used to emulate rotational forces, such as load torques on a driveshaft. The testbed’s fast hardware connections enable real-time testing. The scope of the design was in mechanical design and in specification of the hardware components. Initial Internal Combustion Engine (ICE) steady-state and transient tests were done to partially validate the testbed. However, the performance was assessed to not be at an acceptable level. For example, only speed tracking passed the non-road transient cycle tracking assessment. Torque tracking and the derived power curves failed the assessment narrowly. However, the test results indicate that with proper tuning of the control software, the system performance should get better. The system response was slow at this point, but the transient behavior itself was fast. Also, in steady-state, torque and speed ripple were low. Only the preparations for HIL simulation were carried out, since the testbed was not validated to be functional enough for the much more demanding HIL tests. The preparations involved building a simulation model of a series-parallel hybrid Refuse-Collecting Vehicle (RCV), which is to be used for the verification of the designed system’s HIL capabilities. The model was independently verified to be suitable to be used for the physical tests.Viimeaikaiset muutokset ajoneuvojen tyyppihyväksyntään ovat lisänneet tarvetta testausmetodeille, jotka paremmin vastaavat oikean elämän ajo-olosuhteita. HIL-simulaatio nähdään houkuttelevana vaihtoehtona pelkälle simulaatiolle sekä ajoneuvon ajonaikaisille mittauksille. Tämän työn tavoitteena on tarjota toimiva testilaite moottoridynamometritestaukseen sekä hybridiajoneuvojen HIL-simulaatioihin. Lisäksi, HIL:in nykytilanteen kuvausta pidettiin tärkeänä työn tavoitteena. HIL:in, ja yleisemmin reaaliaikaisen testauksen, tausta ja teoria selvitettiin laaja alaisesti käyttäen esimerkkejä hybridivoimanlähteisiin liittyvistä ajoneuvoalan käyttökohteista. Kirjallisuutta hyödyntäen, testipenkki suunniteltiin ja rakennettiin. Testipenkkiä voidaan käyttää emuloimaan pyöriviä voimia, kuten vetoakseliin kohdistuvia vääntöjä. Testipenkin nopeat yhteydet mahdollistavat reaaliaikaisen testauksen. Suunnittelu oli rajattu pääasiassa mekaaniseen suunnitteluun ja komponenttien määrittelyyn. Sähkö- ja ohjelmistosuunnittelu määriteltiin yleisellä tasolla. Alustavat polttomoottorilla tehdyt vakaiden ajopisteiden ja transienttiajojen testit toteutettiin testipenkin osittaiseksi validoinniksi. Kuitenkin, laitteen suorituskyky ei yltänyt halutulle tasolle. Esimerkiksi, ainoastaan nopeusseuranta läpäisi transienttiajo testin, mutta vääntö- ja voimaseurannat epäonnistuivat täpärästi. Tulokset kuitenkin osoittavat luottamusta siitä että testipenkki saadaan aikanaan halutulle tasolle ohjelmistopuolen kontrollereja säätämällä. Tällä hetkellä systeemin vasteaika on liian pitkä, vaikka muuten dynamiikka on nopeaa. Lisäksi, vakaissa ajopisteissä vääntö- ja nopeushuojunta ovat alhaisia. Ainoastaan valmistelut HIL-simulaatiota varten saatiin toteutettua, sillä testipenkkiä ei saatu reaaliaikasta testausta vaativalle tasolle. Valmistelut sisälsivät hybridijäteauton simulaatiomallin rakentamisen, jota tullaan aikanaan käyttämään testipenkin HIL toimivuuden validointiin. Simulaatiomalli varmistettiin itsenäisenä toimivaksi, ja siten soveltuvaksi tuleviin fyysisiin testiajoihin